A Novel Dye-Sensitized Solar Cell Structure Based on Metal Photoanode without FTO/ITO

Traditional dye-sensitized solar cells (DSSC) use FTO/ITO containing expensive rare elements as electrodes, which are difficult to meet the requirements of flexibility. A new type of flexible DSSC structure with all-metal electrodes without rare elements is proposed in this paper. Firstly, a light-receiving layer was prepared outside the metal photoanode with small holes to realize the continuous oxidation-reduction reaction in the electrolyte; Secondly, the processing technology of the porous titanium dioxide (TiO2) film was analyzed. By testing the J–V characteristics, it was found that the performance is better when the heating rate is slow. Finally, the effects of different electrode material combinations were compared through experiments. Our results imply that in the case of all stainless-steel electrodes, the open-circuit voltage can reach 0.73 V, and in the case of a titanium photoanode, the photoelectric conversion efficiency can reach 3.86%.

Electrical Impedance of Surface Modified Porous Titanium Implants with Femtosecond Laser

The chemical composition and surface topography of titanium implants are essential to improve implant osseointegration. The present work studies a non-invasive alternative of electrical impedance spectroscopy for the characterization of the macroporosity inherent to the manufacturing process and the effect of the surface treatment with femtosecond laser of titanium discs. Osteoblasts cell culture growths on the titanium surfaces of the laser-treated discs were also studied with this method. The measurements obtained showed that the femtosecond laser treatment of the samples and cell culture produced a significant increase (around 50%) in the absolute value of the electrical impedance module, which could be characterized in a wide range of frequencies (being more relevant at 500 MHz). Results have revealed the potential of this measurement technique, in terms of advantages, in comparison to tiresome and expensive techniques, allowing semi-quantitatively relating impedance measurements to porosity content, as well as detecting the effect of surface modification, generated by laser treatment and cell culture.

THE STUDY OF THE SORPTION PROPERTIES OF FILTERING MATERIALS BASED ON TITANIUM PHOSPHATE - POROUS TITANIUM COMPOSITION

Inorganic sorbents are more selective in comparison with commercial ion exchange resins towards of metal ions. However, inorganic sorbents characterized not high kinetic properties. One of the way to increase the kinetic rate of inorganic sorbents is to reduce the particle size of these materials, other way is synthesizing inorganic sorbents as porous products from powder materials. A sample of such inorganic sorbents is titanium phosphate of various compositions. Studying the properties of microfilters based on composition titanium phosphate - porous titanium has been developed. The sorbents based on acidic titanium phosphate Ti(HPO4)2∙H2O were used for filtering solution with Fe(II) content. It is found that the number of impregnations with inorganic sorbent modificator is important and influence filtration process. The obtained results demonstrated that after the first impregnation of porous material with a smaller pore size, it is possible to obtain such sorbent as a mass content of powder material. By varying the ionic form of titanium phosphate, the porosity of titanium, the amount of impregnation, it could be possible effect on the sorption Fe(II). The sorption properties of titanium-titanium phosphate microfilters were studied by potentiometric titration in the NaCl-NaOH system, as well as the sorption of Fe2+ ions. The degree of purification for Fe(II) from solution with a concentration of 10 mg/l is 64 %. Application an electric potential to the microfilter of porous titanium - phosphate titanium increases the degree of purification of Fe(II) to 88 %.

Thin TiO2 Nanocoating of Porous Titanium through Radio Frequency Magnetron Sputtering to Improve the Biological Response of Orthopedic Implants

: The present study applied a TiO2 nanocoating on a titanium foam substrate produced by powder metallurgy through magnetron sputtering. Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD) were employed to investigate the surface morphologies of the porous specimens and pre- and post-coating phases, respectively. Also, the growth and proliferation of MG-63 cells (osteoblasts) and their attachment and proliferation on the coated porous titanium specimen (relative to the uncoated specimens) were studied using in vitro and methyl thiazol tetrazolium (MTT) cytotoxicity tests. Considering the porous macrostructure of the coated titanium specimen and the nanostructure of the TiO2 coating on the porous surface and macro-pore walls, the coated specimen was found to be effective in the biocompatibility improvement of dental and orthopedic implants.

The Effects of Graphene on the Biocompatibility of a 3D-Printed Porous Titanium Alloy

3D-printed titanium (Ti) materials have attracted much attention in the field of bone tissue repair. However, the combination strength of traditional alloy materials with bone tissue is lower, and the elastic modulus is higher than that of natural bone tissue, which makes the titanium alloy susceptible to stress shielding phenomena after implantation. Therefore, it is urgent to find better surface modification technology. In this study, the physical and chemical properties, toxicity, and proliferation of adipose stem cells of composite graphene-coated titanium alloy (Gr–Ti) were investigated using 3D-printed titanium alloy as a material model. Physical and chemical property tests confirmed that 3D printing could produce porous titanium alloy materials; the compressive strength and elastic modulus of the titanium alloy scaffolds were 91 ± 3 MPa and 3.1 ± 0.4 GPa, matching the elastic modulus of normal bone tissue. The surface characterization shows that graphene can be coated on titanium alloy by a micro-arc oxidation process, which significantly improves the surface roughness of titanium alloy. The roughness factor (Ra) of the Ti stent was 4.95 ± 1.12 μm, while the Ra of the Gr–Ti stent was 6.37 ± 0.72 μm. After the adipose stem cells were co-cultured with the scaffold for 4 h and 24 h, it was found that the Gr–Ti scaffold could better promote the early cell adhesion. CCK-8 tests showed that the number of ADSCs on the G–Ti scaffold was significantly higher than that on the Ti scaffold (p < 0.01). The relative growth rate (RGR) of ADSCs in Gr–Ti was grade 0–1 (non-toxic). In the in vivo experiment of repairing a critical bone defect of a rabbit mandible, the bone volume fraction in the Gr–Ti group increased to 49.42 ± 3.28%, which was much higher than that in the Ti group (39.76 ± 3.62%) (p < 0.05). In conclusion, the porous graphene–titanium alloy promotes the proliferation and adhesion of adipose stem cells with multidirectional differentiation potential, which has great potential for the application of bone tissue engineering in repairing bone defects in the future.